Oct. 13, 1923 
A New Tumor of the Apricot 
57 
desires to show gratitude, and, more especially, appreciation of the 
interest shown by this philanthropist in the development of agricultural 
science in Palestine, at a time when such interest was generally lacking. 
MORPHOLOGICAL CHARACTERS 
Acervuli. —Black, irregular in shape, frequently circular, sometimes confluent, 
often submerged in solid artificial media, erumpent. Of all sizes, from tiny specks 
to 1, 1 * 4 , and 2 mm., or larger masses when confluent. 
Conidia ®. —Fusoid or oblong-fusoid, straight or curved, or ovoid; three-septate, 
rarely four- or five-septate. Constricted at the septa. The color of mature spores, 
umber, of a shade lighter than Saccardo’s (7). Young spores grade from hyaline or 
subhyaline to dark olive-buff. 10 Basal cell hyaline, occasionally subhyaline; ter¬ 
minal, hyaline. 
Appendages. —Mostly single and curved, occasionally straight and oblique, hya¬ 
line. Forked appendages not exceeding 6 per cent. Extremes for length for 89 
appendages were 3 to 36 p; 8 p was the standard length. The appendages range in 
width from 1 to 2 p at the base, tapering. 
Spore dimensions. —In 120 spores the extreme measurements for length and width 
were, respectively, 12 to 27 /x and 5 to 10 ju; the standard, or the most common, values 
for length and width were 16 to 17.5 jx and 6.5 to 7 fx, respectively. * 11 
Plate 12 shows some characteristic spores of Monochaetia rosenwaldia . 
Of these, the spores lettered A, C, E, and J represent the most common 
types. Plate 12, K-P, shows irregular forms, varying from the standard 
with regard to the number of the cells. Such variations were very rare. 
Q and W, on the same plate, show variations in the apical appendages. 
CULTURAL CHARACTERS 
On standard nutrient agar. —Plate 13, A, shows a 6-day-old colony in a Petri 
-dish culture of this medium at a magnification of X2. The growth of the fungus, 
which is very vigorous at first, often becomes arrested. Acervuli form rarely. The 
mycelium penetrates but little into the interior of this medium. 
On prune juice agar. —Plate 13, B, shows a 9-day-old colony in a Petri dish 
culture of this medium at a magnification of approximately X 1 H- Note the 
zonate character of the growth. This is a feature which has not been observed 
on the other media. Note also the formation of acervuli from white masses of myce¬ 
lium. The acervuli on this medium are often globular and raised. 
On shear’s agar. —The growth of the fungus takes place largely in the interior of 
the medium; only occasionally does the mycelium spread on the surface. The 
acervuli are erumpent or submerged, forming at about the same time as in the previous 
medium—namely, when the colony is about 10 days old. A faint zonation is some¬ 
times noticeable in very young cultures but soon disappears. 
Growth in standard nutrient broth. —At first somewhat zonate. When the 
surface of the liquid has been reached a white, woolly pellicle is formed. Acervuli 
at first usually submerged in the mycelium, erumpent at maturity. They rarely 
form before three to four weeks. 
Growth on infusions of Moorpark apricot leaves. —Very vigorous and rapid. 
A series of cultures was carried on in infusions of beets, carrots, tur¬ 
nips, and Irish potatoes. No distinction could be noticed in the growth 
produced in these media. Apart from the acervuli, which in these 
cultures formed somewhat earlier than on the other media, the growth 
was not characteristic. Acervuli were recognizable at the end of the 
week and formed in large abundance, notably on Irish potatoes. In 
this medium nearly all the vegetative mycelium was soon covered with 
continuous jet-black masses of spores. These vegetable media may be 
used to advantage when large quantities of spores are required. 
9 The material for the study of the spores was obtained from acervuli on the inoculations. 
10 Ridgway, Robert. Color standards and color nomenclature. 43 p., 53 col- pi. Washington, 
D. C. 191a. 
11 The suggestion for the use of this mode of expression in the description of spores was first made by Dr. 
E. P. Meinecke (6) in preference to the usual way, in which only the extreme dimensions are stated. It is 
obvious that a much better idea of the size of the objects can be formed when the standard or most common 
dimensions are taken into consideration along with the extremes. 
